1. Technical Field
The present invention relates to a compressed air supply system and a vehicle comprising (including, but not limited to) such a compressed air supply system. The invention relates more particularly to a compressed air supply system comprising an adjustable fan, which is arranged to generate an air flow for cooling compressed air generated by the compressor should the temperature of the compressed air be deemed to be too high.
2. Background
Compressed air supply systems generally comprise a compressor, compressed air lines, one or more active components and one or more compressed air tanks, which are fed by the compressor. When the compressor compresses the air, the air is heated. If high pressures are to be obtained, the compressed air attains a high temperature, which in a normal compressed air system on a heavy truck with a system pressure of 13 bar can reach approximately 300° C. A temperature of this order of magnitude is harmful to components forming part of the pneumatic system, such as seals of polymer material, for example.
Hot air furthermore absorbs a greater quantity of water than cold air, so that the load on air dryers connected to the compressed air supply system increases if the incoming air has a high temperature. In addition, the drying agent in the air dryers has a lower efficiency at high temperatures.
In order to ensure efficient functioning, the air on entry to the air dryer should preferably have a temperature of less than 60° C. This can be achieved by fitting a first component at a sufficiently large distance from the compressor, so that efficient cooling is obtained. This solution has the disadvantage, however, that it is difficult to design the piping with a continuous fall in the case of a long piping. This means that the pipe must be bent, thereby creating pockets in which water can accumulate, with a resultant risk of ice plugs forming in cold weather.
In order to reduce the risk of ice plugs occurring, vehicles have been provided with a pneumatic system comprising a short and continuously falling piping up to a first component in the form of an air dryer. In order to ensure that components of the air dryer are not damaged by excessively hot air, the air line has been fitted so that it passes by the air flow from the cooling fan that forms part of the vehicle cooling system. This fan is controlled independently of the cooling requirement of the compressed air, which leads to a risk of overheated air reaching the air dryer.